The goal is to further establish artificial breeding of chimpanzees as an effective means for increasing the birth rate at facilities in the United States which house populations of these animals. Three specific objectives form the basis for the specific aims of the project. First, the effectiveness of artificial insemination methodology will be improved by evaluation of the type of hormone treatment used to induce and synchronize ovulation time. The optimum route for semen delivery, and the minimum semen quality and optimum concentration will be determined. Second, improved methods for cryopreservation of semen from chimpanzees will be evaluated and monitored using in vitro tests designed to identify maintained fertilizing capacity and morphological integrity. Third, a semen bank will be established primarily for chimpanzee semen, with addition of other ape semen when available. This artificial breeding program should 1) be inexpensive to maintain, 2) provide additional knowledge concerning the reproductive physiology of the great apes, and 3) be adaptable to zoos desiring to improve their own colonies of these animals. Just as important will be the maintained integrity of these animals through maximum use of the gene pool. It is essential to provide a continued and adequate supply of great apes, particularly chimpanzees, for biomedical research in to human health-related problems for which they are the only applicable models, and this research is a sensible and necessary adjunct to development of a National Breeding and Research Program.